Metatungstates of sodium and ammonia are known in the art. Sodium metatungstates [Na.sub.6 (H.sub.2 W.sub.12 O.sub.40).3H.sub.2 O] and ammonium metatungstate [(NH.sub.4).sub.6 (H.sub.2 W.sub.12 O.sub.40).3H.sub.2 O] display high solubilities in water and other solvents. The high solubilities of metatungstates make them useful, among uses, as catalysts.
A use of sodium metatungstate and ammonium metatungstate, which use relies both on the high densities and solubilities of these compounds, is disclosed in U.S. Pat. No. 4,557,718. This patent discloses the use of metatungstate solutions for heavy media separation processes. High concentrations of sodium metatungstate dissolved in water provide true solutions, as distinguished from solutions having finely divided solids suspended therein, having densities up to about 3.1 grams per cubic centimeter (g/cc).